EP0347462A1 - Device for magneto-abrasive machining of external cylindrical surfaces of parts - Google Patents

Abstract

The essence of the device is that the electromagnetic system is provided with an additional pair (3) of pole pieces (5), which compared to the first pair (2) with respect to this along the longitudinal axis (0 ₁ -0 ₁ ) of machining workpiece (15) is offset by the distance L = (0.2 to 1.0) D, where D is the diameter of the pole shoes, the pole shoes (4 and 5) in each pair (2 and 3) being kinematically connected to one another , have a common axis of rotation (0-0) and are mounted with an eccentricity (e) of opposite sign with respect to this axis.

Description

Technical field

The present invention relates to the field of grinding workpieces, in particular to a device for magnetic grinding of cylindrical outer surfaces of workpieces.

Underlying state of the art

A device is known for descaling wire by drawing it through ferromagnetic powder that is compressed between two disks (SU, A, 787 131). One of the disks is designed to be rotatable and provided with beads for holding the powder. The second disc is cushioned and is used for mechanical compression of the powder in the processing area.

The known device does not guarantee high quality in the treatment of the wire, especially if it is made of soft and tough alloys, because mechanical clamping of the grinding powder in the work area leads to embedding of the abrasive in the machined surface. This phenomenon can be avoided by reducing the pressure of the pressure disc on the powder, but the performance of the process drops dramatically.

The device according to the invention comes closest to a device for the magnetic grinding of cylindrical outer surfaces of workpieces, namely for descaling or derusting wires or heavy rolled products (SU, A, 975 134).

The known device for magnetic grinding processing includes: an electromagnetic system with a pair of pole pieces, which are arranged opposite one another and form an annular working area, and a device for longitudinally feeding the wire or the heavy rolled product into the working area.

In the known device, the pole shoes are designed as disks, which are arranged opposite one another in the end faces of an electromagnetic coil and have a center bore for the through run of the wire or the heavy rolled goods.

The inner cavity of the coil between the pole pieces is filled with ferromagnetic grinding powder, while the actual pole pieces are covered on the outside with non-magnetic covers.

As is known, when the electrical current is supplied to the electromagnetic coil, a magnetic field of the coil is generated, the lines of force of which lie parallel to the coil axis within the coil. The ferromagnetic abrasive powder particles inside the coil are magnetized and form chains that are stretched along the magnetic lines of force. The largest axis of the ferromagnetic abrasive powder particles is oriented along the magnetic lines of force. The wire or rod to be processed runs through the center holes of the pole pieces along the longitudinal axis of the coil, deforms the chains from the abrasive powder particles and shifts them in the radial direction, forming new, denser chains that are stretched along the magnetic lines of force. The abrasive particles scratch the surface to be machined and remove the surface layer from the workpiece. However, the surface is only processed with the particles from the chains that are closest to the lines of force. The blunting of the cutting edges of the particles affects the machining conditions. Since the cutting ability of the particles is not restored in the known device, the dulling of the latter results in an abrupt reduction in the machining performance and goodness. In addition, the fine chips that occur on the surface to be machined when the abrasive particles are scratched are not removed from the working area, but are mixed with the abrasive powder, which also deteriorates the cutting properties of the latter. A small amount of the grinding particles involved in the processing, the contamination of the powder with processing waste, the low pressure of the grinding particles on the surface to be processed as a result of the arrangement of the magnetic lines of force parallel to the feed direction of the Workpiece thus result in a rapid loss of the cutting properties of the ferromagnetic grinding powder and an uneven processing according to the length of the cylindrical surfaces of the workpieces, in particular a wire or rod.

Disclosure of the invention

The invention has for its object to provide a device for magnetic grinding of cylindrical outer surfaces of workpieces, in which the structural design of the electromagnetic system and the arrangement of the pole shoes would allow scale and oxide films to be removed completely and uniformly over the entire surface of the workpiece , which could significantly increase the performance and quality of magnetic grinding.

The object is achieved in that device for magnetic grinding machining cylindrical outer surfaces of workpieces, which contains an electromagnetic system with a pair of pole pieces, which are arranged opposite one another and form an annular working area, and a device for longitudinal feed of the workpiece into the working area , According to the invention, the electromagnetic system is provided with an additional pair of pole pieces, which is offset with respect to the first pair with respect to this along the longitudinal axis of the workpiece to be machined by the distance L = (0.2 to 1.0) D, where D The diameter of the pole shoes is, the pole shoes in each pair being kinematically connected to one another, having a common axis of rotation and being mounted with an eccentricity of opposite sign to this axis.

The pole shoes are arranged so that the magnetic lines of force penetrate the annular working area in a direction perpendicular to the feed direction of the workpiece to be machined. The abrasive powder particles align themselves in chains along the magnetic lines of force and exert the maximum force on the surface to be machined. Effect out.

When the pole pieces rotate, the abrasive powder particles form an annular "cutting brush", run onto the surface of the workpiece to be machined, exert pressure on it, have a grinding effect and push the workpiece away into the cavity between the pole pieces. As the pole pieces rotate further, the powder particles come into contact with the surface of the workpiece to be machined, return to the original position and form the initial cutting contour from the quantity of particles in the form of the ring-shaped "cutting brush". The return of the particles to the starting position is promoted by the shell shape of the pole shoes arranged in pairs, which ensures the greatest value of the mangetic induction in the space between the outer pole edges. When the pole shoes rotate, the surface of the workpiece is continuously processed by the particles in contact with it, while in the diametrically opposite sections of the shoe edges the "cutting brush" distorted in the working area is regenerated (restored) from the abrasive powder particles.

Due to the continuous restoration of the ring-shaped "cutting brush", the particles forming these are always spatially reoriented and change their position in relation to the surface to be processed. Therefore, practically all cutting edges of the particles of the "brush" are involved in the work, which favors the increase in the powder service life and the processing power.

If the workpiece to be machined (wire or rod) continues to move without rotation, only one half of its surface is machined with one pair of pole pieces. For complete machining of the workpiece, the second pair of pole shoes is provided, which is offset by a distance L from the first along the axis of the workpiece with respect to the first pair. The characteristic values of the descaling process are significantly influenced by the size L.

At low values of L (L 0.2D, where D diam water is the pole piece) there is the interaction of the magnetic fields of the two pairs of shoes, the wholeness of the "cutting brush" is disturbed and the processing effect decreases. With relatively large values of L- (L> 1, OD), the dimensions of the device are increased, the magnetic resistance of the elements of the magnetic conductor increases, the size of the magnetic induction in the working area is reduced and the intensity of the process thus decreases.

Brief description of the drawings

• Fig. 1 prinzipielles Schema der erfindungsgemäßen Vorrichtung zur magnetischen Schleifbearbeitung zylindrischer Außenflächen von Werkstücken im Querschnitt;
• Fig. 2 einen Schnitt nach Linie II - II in Fig. 1
• Fig. 3 einen Schnitt nach Linie III - III in Fig 1.

The present invention is explained in more detail below using a concrete example of its embodiment described in detail with reference to the attached drawings, in which it shows:

• Fig. 1 basic diagram of the device according to the invention for magnetic grinding machining cylindrical outer surfaces of workpieces in cross section;
• 2 shows a section along line II - II in FIG. 1st
• 3 shows a section along line III-III in FIG. 1.

Best embodiment of the invention

The inventive device for magnetic grinding of cylindrical outer surfaces of workpieces, for. B. of wire, (as shown in Fig. 1) contains an electromagnetic system that a z. B. on a (not shown in Fig.) Machine bed mounted magnetic conductor 1 and two pairs 2 and 3 vnn pole pieces 4 (Fig. 2) and 5 (Fig. 3). Electromagnetic coils 6 (FIG. 2) are attached to the magnetic conductor 1 and are connected to a direct current source. In the magnetic conductor 1 bearings 7 are attached, on which shafts 3 are supported. In each pair 2 and 3, the pole pieces 4 and 5 are attached to each other on the shafts 8 and form an annular working area 9. In each pair 2 and 3, the pole pieces 4 and 5 are kinematically connected to one another via joints 10, which as Screws are formed with which the pole pieces 4 and 5 are fastened to the shafts 8.

One (not shown in FIG te) device for the rotary drive of the pole shoes 4 and 5 is present, which are driven in rotation by means of a belt drive 11 via a drive pulley 12 mounted on the shaft 8 (in the direction indicated by arrow A in FIG. 2).

In pairs 2 and 3, the pole shoes 4 and 5 are supported with a gap h, have a common axis of rotation 0-0 and are offset from their axis of rotation 0-0 by the size of the eccentricity e with opposite signs. The space between the end faces 13 of the pole shoes 4 and 5 is filled with a ferromagnetic grinding powder 14.

A device for longitudinal feed, which includes rollers 16, is provided in the device for loading the workpiece 15. The device for rotating the rollers 16 is not shown.

For complete machining of the workpiece 15, for example a wire, as shown in FIG. 1, the pair 2 of the pole shoes 4 is along the axis 0 ₁ - 0 _{1 of} the workpiece 15 with respect to the pair 2 of the shoes 5 by the distance L offset. The distance L is set within the limits of (0.2 to 1.0) D, where D is the diameter of the pole pieces 4 and 5.

If L <0.2 D, the magnetic fields of pairs 2 and 3 of pole pieces 4 and 5 interact, and the entirety of working areas 9 is disturbed. With values L> 1.0 D, the size of the magnetic induction in the work area 9 decreases.

The device according to the invention functions as follows. The electromagnetic coils 6 are supplied with electric current, an electromagnetic field is created around the coils 6 and the pole pieces 4 and 5 are magnetized. Under the action of the magnetic field, the powder 14 is compressed in the gaps h between the pole pieces 4 and 5 and forms two ring-shaped work areas 9. The shaft pieces 4 and 5 are set in rotation by means of shafts 8, traction sheaves 12 and belt drives 11 Arrows B and B ₁ rotating rollers 16 is to be processed 15 rotates along the axis 0 ₁ - progressively moves 0 ₁ according to the arrow S and between the pairs 2 and 3 of the P _o lschuhe 4 and 5 advanced so that its axis 0 ₁ - 0 _{1 represents} a tangent to the outer surfaces of the annular regions 9 filled with the powder 14.

If the shoes 4 and 5 are arranged in pairs 2 and 3 on the same axis of rotation 0-0, each pair 2 and 3 processes its surface half of the workpiece 15. At the boundaries of these machined halves, the metal decrease is less than in the other surface areas. In order to guarantee the processing of the entire surface and to increase the uniformity of the metal removal, the pole shoes 4 and 5 in each pair 2 and 3 are offset in opposite directions with respect to the axis of rotation 0-0. H. with the eccentricity e of opposite sign. When the pair 2 and 3 of the pole shoes 4 and 5 revolve with an “opposite-phase radial stroke”, the powder particles 14 in this case, as it were, oscillate along the circumference of the surface to be machined. As a result, each pair 2 and 3 of the shoes 4 and 5 does not process half, but rather the largest surface part of the workpiece 15; the surface sections machined with each pair 2 and 3 are partially covered from one another, the uniformity of the descaling increases.

Specific examples for the implementation of the device example 1

Magnetic grinding of a rod made of titanium-tungsten alloy with diameter d = 5 mm and initial surface roughness R _a = 1.0 to 0.8 µm. Technological conditions of descaling: linear rotation speed of the pole shoes 4 m / s; Feed speed 0.05 m / s; Working gap size 1.5 mm; magnetic field strength in the coils 120 A / m. Pole shoes with a diameter of 146, 90 and 122 mm were used, which were set at different distances L and with different eccentricity e were. Ferromagnetic abrasive powder Pe-TiC (40%) with a grain size of 315/100 µm and coolant was used. The descaling results are summarized in a table.

Example 2

Magnetic grinding of a welding wire made of aluminum-magnesium alloy with a diameter d = _1, 0 mm and output surface roughness R _a = 0.8 to 0.6 microns. Technological conditions are the same as in Example 1. The table shows the results obtained.

In the examples given, the metal mass g, which is removed from a unit area of the machined surface, serves as the characteristic value of the machining performance. The quality of the descaling was assessed according to the parameter R _{a of} the machined surface.

• g = 4,8 bis 6,3 mg/cm² und R_a = 0,12 bis 0,25 µm für Beispiel 1;
• g = 6,0 bis 8,1 mg/cm² und R_a = 0,10 bis 0,18 µm für Beispiel 2.

The maximum values of the performance and the quality of the processing were achieved in experiments 5, 6, 15 to 18 (example 1) and experiments 23, 24, 33 to 36 (example 2):

• g = 4.8 to 6.3 mg / cm ² and R _a = 0.12 to 0.25 µm for Example 1;
• g = 6.0 to 8.1 mg / cm ² and R _a = 0.10 to 0.18 µm for Example 2.

The test results show that the distance between the pairs of pole pieces L ⁼ (0.2 to 1.0) D is optimal. At L <0.2, the entirety of the "ring brush" made of powder is disturbed by the interaction of the magnetic fields of the pole shoes and the characteristic values of the process are deteriorated. With L> 1, OD, the dimensions of the magnet system and its magnetic resistance increase, as a result of which the magnetic induction in the working gaps decreases and the characteristic values g and R _{a are} reduced.

The best parameters were obtained for the treatment with sizes of eccentricity e = (0.3 to 3.0) d. At e <0.3d there is uneven machining of the workpiece circumferentially, and at 2> 3, Od the "ring brush" made of powder is destroyed during the machining process, as a result of which the machining performance and quality decrease.

Comparative experiments were carried out on the invention Device and a known device made. When machining a rod made of tungsten-titanium alloy with a diameter of 5 mm using a known device, the values g = 4.5 mg / cm ² and Ra = 0.28 μm were obtained, while machining a wire made of aluminum-magnesium Alloy with 1 mm diameter by means of the device according to the invention was g = 5.6 mg / cm ² and R _a = 0.21 μm. The tests showed that compared to a known device the performance of the invention is 1.4 times, while the quality is 2.1 to 2.3 times higher.

The device according to the invention for magnetic grinding of cylindrical outer surfaces of workpieces enables high machining quality by producing an elastic contact between the machining tool (ring brush made of powder) and the workpiece to be machined and the workpiece are avoided, thereby preventing possible penetration of the powder particles into the body of the workpiece and abrasive embedding in the surface to be produced.

The high performance during operation of the device is due to the continuous reorientation of the powder particles in the ring-shaped working area and the fact that practically the entire powder mass is involved in the work.

Commercial usability

It is most convenient to use the device for polishing and cleaning rods, tubes, wires, narrow metal strips of oxide films and scale layers.

Claims (1)

Device for magnetic grinding of cylindrical outer surfaces, of workpieces which form an electromagnetic system with a pair (2) of pole pieces (4) which are arranged opposite one another and form an annular working area (9), and a device (16) for longitudinally feeding the workpiece in contains the work area, characterized in that the electromagnetic system is provided with an additional pair (3) of pole pieces (5) which is opposite the first pair (2) with respect to the latter along the longitudinal axis (0 ₁ - 0 ₁ ) of the machining workpiece (15) is offset by the distance L = (0.2 to 1.0) D, where D is the diameter of the pole pieces (4, 5), the pole pieces (4, 5) in each pair (2, 3 ) are kinematically connected to each other, have a common axis of rotation (0 - 0) and are mounted to this axis with opposite eccentricity (e).

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